Here's the all-time list of longest-running scripted primetime dramas on the major American networks (hour or half-hour) through the 2015-2016 season, (hence no Simpsons, 2 1/2 Men, Baywatch, Survivor, 60 Minutes, etc.) and reboots (90210/Five-O/etc.) don't add to the original series' longevity. Major networks are CBS, NBC, ABC, FOX, and CW (or WB/UPN if show was mid-2000s or earlier).

T-1. Gunsmoke, 20 seasons
T-1. Law & Order, 20 seasons
T-3. Lassie, 17 seasons
T-3. Law & Order: SVU, 17 seasons
5. CSI: Crime Scene Investigation, 16 seasons
6. ER, 15 seasons
T-7. Bonanza, 14 seasons
T-7. Dallas, 14 seasons
T-7. Knots Landing, 14 seasons
10. NCIS, 13 seasons
T-11. Hawaii Five-O, 12 seasons
T-11. Murder, She Wrote, 12 seasons
T-11. NYPD Blue, 12 seasons
T-11. Grey's Anatomy, 12 seasons
T-15. 7th Heaven, 11 seasons
T-15. Criminal Minds, 11 seasons
T-15. Supernatural, 11 seasons
T-15. Bones, 11 seasons
T-19. Beverly Hills, 90210, 10 seasons
T-19. JAG, 10 seasons
T-19. CSI: Miami, 10 seasons
T-19. Smallville, 10 seasons
T-19. The X-Files, 10 seasons

Forgot Stargate SG-1 10 seasons but was on the Sci-Fi Channel.

Forgot Stargate SG-1 10 seasons but was on the Sci-Fi Channel.This list just included broadcast networks.

I love 7th Heaven! :) :) :)

God bless you always!!! :) :) :)

Holly

P.S. Does them 14 years of Dallas include the more recent seasons of the show?